So two weeks ago I brought my 03 sable (with the 24v duratec) in to have a loose heat shield removed. While it was in, during their normal inspection they recommended new spark plugs due to age/mileage. Going to work the next day suddenly the engine starts misfiring for the first time ever and I brought it back to have them tell me it’s the spark plugs and I need to have them replaced for $1100. Next day, engine is misfiring again. I brought it back and they said it was a faulty spark plug so they replaced it for free. Today, a week later, I suddenly end up in limp mode, with almost no acceleration (with low RPMs) and no check engine light. Turned car off and on again and it’s fine. Could this be related to spark plugs or could they have been wrong about the spark plugs from the start? Could they be sabotaging my car for money? The whole spark plug ordeal seems very suspicious.